Australia’s Amazing Kangaroos and the Birth of Their Young

Among the world’s most curious creatures is Australia’s amazing kangaroo. He appears standing proud and tall on the Australian coat of arms, and has been a rallying symbol for national sporting teams.

Benign of face, bottom-heavy of build, kangaroos outclass most of the animal kingdom in the long and high jump, boxing, and karate. Born a mere 1-1.5 centimetres (half-inch) long, and weighing less than a gram, kangaroos can grow taller than a man. As with most other marsupials, one of the three orders of mammals, they raise their young in body pouches. But kangaroos have another advantage - an expectant female can retain an embryo in ready reserve for months, until the conditions are right for its continued development.

When it comes to marsupials, no place on earth can count a greater variety than the island continent of Australia. Of 250 existing species, some 170 of them - including wombats, bandicoots, and kangaroos live only in Australia or its immediate surroundings. All the rest, except the opossum found in the United States and Canada, are limited to Latin America.

Large, Swift and Powerful

Among marsupials, the Australian grey and red kangaroos are largest. Full-grown males, called boomers, may stand more than two metres tall (seven feet) when fully erect, and weigh close to 90 kilograms (nearly 200 pounds). Yet, bounding across the countryside on highly developed hindlegs, these incredible animals cruise at speeds between 20 and 25 kilometres an hour (12-15 miles per hour). If the need arises, they can accelerate to more than twice that speed. Even speeds of about 48 kilometres an hour (30 miles per hour) may be attained for short distances when these animals are pressed in relatively open country.

While grey kangaroos excel at high-jumping, red kangaroos usually win at long-jumping. Young grey kangaroos have been known to clear a two-metre (seven-foot) high fence with plenty of clearance, while red kangaroos have been known to cover more than 6.1 metres (20 feet) on flat ground with a single bound. On the other hand, one great grey kangaroo’s jump on the flat has been measured at nearly 13.5 metres (44 feet). Incredible!

Of all the distinctive types of marsupials, only kangaroos are bipeds, moving more naturally on two legs than four. Their foreshortened upper limbs terminate in clawed paws used with almost human dexterity in eating, grooming, and self-defence. But the large kangaroo’s real power in flight or fight comes from its elongated rear legs.

On the Move

Ungainly at a four-footed walk, the kangaroo becomes as graceful as a ballerina and considerably more airborne as it shifts to a biped bounce. Along the way it must go into some kind of internal overdrive; experiments show the roo expends no more energy at high speeds than it does at slow speeds.

The animal’s heavy tail, long prized for soup and meat, does more than go along for the ride. On the run it bends at the end like a boomerang and acts as a counterbalance, keeping the creature on an even keel. At a stand still it serves as a sort of stool. If backed into a comer, a kangaroo will stand on its tail and strike vicious blows with the dagger-like claws of both its hindfeet, capable of disembowelling its victim.

In Australia’s sparsely settled inland, locally known as the ‘outback’, it is hard to find an area completely free of kangaroos. Kangaroos live in almost every environment of the Australian bush - scrubland, shrubland, grassy plains, swamps, rock ledges, forests, and even tree tops. The kangaroo inventory, however, divides into two major groups-the rat kangaroo subfamily, which is made up of nine of the smallest species, and the true kangaroo subfamily that encompasses all the sizes of kangaroos from the large red kangaroos down to the wallabies, euros, and wallaroos.

What colour is a Red Kangaroo?

Not all red kangaroos are red. Most males are pale red to brick red in colour but occasional blue-grey males occur. Females are usually blue-grey and in consequence are often called ‘blue fliers’ but, in some areas, both sexes are reddish. Under favourable environmental conditions females become sexually mature when 15-20 months old; males when about two years old. Adult coat colour is established at this stage but, for several years thereafter, both sexes continue to increase in size and to cut molar teeth.

Red Kangaroo

As the largest and most prolific of its kind, the red kangaroo has been extensively studied. The red kangaroo lives over most of the central part of Australia in areas where rainfall averages less than 500 millimetres (barely 20 inches). Within this expansive area, which includes all manner of scrubland, shrubland, grassland and desert, the red kangaroo has a preference for open plains habitats, but is seldom found in regions devoid of shade from scattered trees. ‘Mobs’, the Australian word for ‘herds’, are mobile and semi-nomadic, their movements not being restricted by artificial barriers such as fences designed to keep in wandering sheep or cattle.

The red kangaroo is a grazing animal with a preferred diet of green herbage, including grasses and dicotyledonous flowering plants, and its local distribution is frequently influenced by the availability of this food. Eating takes place mostly at night (like many other Australian mammals that are similarly nocturnal), but may begin in the late evening and extend into early morning. The kangaroo’s forestomach is designed for digestion of food rich in cellulose. Although frequently observed to drink at stock watering places, the red kangaroo appears to be able to exist in the absence of fresh surface water, provided it has access to at least some green hearbage. On mild days it may bask in the sun, but under hot conditions it seeks any available shade.

Birth of a Red Kangaroo

A topic which has been the subject of great controversy over the years has been the manner of birth of the kangaroo’s young and the means by which it gets into its mother’s pouch and becomes firmly attached to a teat. It was once a common belief that the young formed on the end of a teat by some process of budding-off, a fanciful supposition even held by the famous nineteenth century English anatomist, Sir Richard Owen.

The newborn young of the kangaroo is very small, when compared in size with its mother, and after it becomes attached, the teat swells in its mouth so that it can be removed only with difficulty. If roughly pulled off, the young may be injured or torn so that it bleeds. Observations such as these no doubt led many to deduce the theory that a young kangaroo is formed on the end of the teat.

Birth and the associated behaviour of the mother have now been studied in much greater detail in the red kangaroo than in any other marsupial, so a more accurate description of the kangaroo’s birth is now possible.

A mature female which is appropriately nourished, and which is not suckling a young in its pouch already, becomes fertile at approximately 35 day intervals and is thus, like the male, potentially fertile throughout the year. Pregnancy does not interrupt recurrence of fertility.

Lifestyles and Lifespans

Among many species, kangaroo society appears to be a rather casual affair, with individuals drifting in and out of small groups without any long-term commitments.

The usual group consists of a dominant male, a number of adult females, and juveniles of both sexes, but it may include as few as two animals or as many as several hundred. Thus, the old male who has battled his way to ‘bossroo’ finds himself with an ever-changing following. This doesn’t reduce his ferocity, however, should another male challenge his authority. These small groups, or mobs, can become sizable, particularly when they gravitate to the same sources of food and water. Small groups of young males are quite common, and old, scarred males may live as solitary individuals.

Almost half of all young that are born fail to reach two years of age, and 90 per cent die before reaching the age of 10. A few kangaroos may reach the ripe old age of 20, but normal lifespan in the wild seldom exceeds seven years.

Wedge-tailed eagles, pythons and goannas (large native Australian lizards) prey on small roos, and dingoes (native wild dogs) kill adults. But the most devastating enemy is drought. When streams and waterholes dry up, so (too often) does the vegetation on which most kangaroos depend for an alternative source of water as well as food. Joeys in and out of the pouch die at increasingly earlier ages. Periods of extreme drought may delay the onset of maturity in female kangaroos and lead to suppression of their fertility cycles. At the same time most fertile females cease to breed. As a drought worsens, fewer and fewer females have joeys either at foot or in their pouches.

After two years of drought a population may include females aged three years or more which have never produced young, while none of the kangaroos in the area would be younger than two, the precise duration of the drought. Every kangaroo born during that period of drought would have died. Following rainfall and growth of new herbage, kangaroos come into breeding condition almost immediately. However, it can take as long as eight years for kangaroos, even though prolific breeders, to reach their pre-drought numbers again.

Fertility Cycle

The young is born 33 days after mating, and mating can occur again a day or two after this. The embryo resulting from the mating remains in a quiescent state until the previous young is about to vacate the pouch. During this period the suckling stimulus prevents the recurrence of fertility cycles. If the young is lost prematurely from the pouch, the quiescent embryo resumes development (as is normal at the end of pouch-life) and cyclic reproductive activity is resumed.

There are no external signs that the kangaroo is pregnant and the first indication that birth is imminent is when the mother begins to clean her pouch. About 24 hours or more before birth, the pregnant female begins to lean forward and put her head inside the pouch, which is usually held open by the forepaws, and licks, and perhaps bites, the inside of her pouch. This pouch-licking continues as the female assumes a birth position, the tail passing between her hindlegs, hindquarters resting on the ground and back supported against a tree or other object. The pouch-licking becomes more intense as birth approaches.

At the point of birth the young appears head first enclosed in the amniotic sac, and either the continued vigorous licking by the mother, or maybe the sharp claws of the young (or a combination of both factors), causes the sac to rupture. In any case, the hairless newborn almost immediately breaks free and begins its journey to the pouch.

Up to the Pouch

The newborn young crawls over the mother’s fur by grasping the fur with alternate movements of the forelegs and claws. The hindlimbs play no part and are mere buds at this stage. Simultaneously with the movements of the forelimbs, the head is moved from side to side and the young appears to move in a sinuous manner over the fur. For part of the journey the umbilical cord is attached to the yolk sac inside the mother, but it is finally broken, probably by the licking of the mother or perhaps occasionally by the pulling of the young. The young reaches the pouch and disappears inside. Crawling behaviour and head movement continue until it finds a nipple and attaches. The journey is accomplished in a remarkably short time - on average in less than three minutes. It is not known how long the young takes to attach to a nipple, but it is certainly shorter than 15 minutes.

The pouch contains four teats. The mother offers no resistance to the young and, indeed, appears to be quite oblivious of its existence. While the young is crawling to the pouch, the mother is vigorously licking up the blood and birth fluids, carefully cleaning all traces from her fur. This licking is done after the young has gone, although she occasionally licks over or ahead of the young while it is crawling to the pouch, thus giving rise in some people’s minds to the idea that the mother prepares a well licked track for the young to follow.

There is, in fact, no necessity to postulate that the young needs assistance to get to the pouch and attach to a teat, for it is endowed with all the necessary equipment at birth. It has well-developed and active forelimbs, jaw muscles and tongue. Although it has no functional eyes or ears, it has large nostrils and presumably a well-developed sense of smell which probably plays a major part in its location of the pouch. It has often been stated that the newborn young is incapable of sucking and the mother therefore forces milk into its mouth by means of certain abdominal muscles, but this is incorrect.

The life of a Joey

During the pouch-life of the young the mother keeps both pouch and young clean by inserting her muzzle and licking many times daily. She appears to have no maternal interest in the young while it is small and hairless, but by the time it begins to get out of the pouch the mother/young attachment is very strong. Young kangaroos are known as joeys, and the young red kangaroo joey first gets out of the pouch at about 198 days of age, but only a few minutes of the day are spent out at this age. The young vacates the pouch entirely at an average age of 235 days, and in the last few days about half of the time is spent out of the pouch.

The mother cooperates to facilitate the reentry of the young. She bends her body downwards and spreads her forelegs, and if the young is small and inexperienced, she brings her body closer to the ground by inclining her hindlegs backwards. The young approaches from the mother’s front and begins feeling for the pouch from the neck region. When it finds the pouchroom it grasps it and goes in head-first, turns a complete somersault, and brings the head towards the entrance.

If the young is temporarily lost, the mother runs around looking for it and calls loudly. The young also calls loudly and this call brings not only its mother but other female kangaroos as well. When the young is found the mother adopts the posture which facilitates entry to the pouch and at the same time produces a special clucking call.

Standing Roo Only

At the end of pouch-life the female restrains the young from entering the pouch by grasping it firmly with her forepaws or by making off as it tries to enter. If a large joey-at-foot reentered the pouch after the birth of a new pouch-young, it would kill it, but this seems not to occur, so the mother’s methods of restraining the young joey at-foot are apparently effective. Some mothers have even been known to succeed in convincing their large joeys to leave the pouch simply by relaxing the pouch and letting the joey tumble out.

Upon leaving the mother’s pouch, the joey is in the form of a miniature adult weighing four to five kilograms (8-1/2 to 11 pounds). Now following its mother at heel, the joey continues to suckle from outside for a further four months until it is about a year old. It continues to associate with its mother for a considerable time after weaning.

Continuous Reproduction

Meanwhile the joey’s younger sibling in the pouch suckles from another teat. A remarkable feature of lactation is concurrent production from different mammary glands of milk of different chemical composition: the teat on which the pouch-young feeds delivers milk with much less fat than the one which serves the young outside the pouch.

The female red kangaroo’s pouch and reproductive tract is seldom empty in a remarkable assembly line of life. Given favourable conditions, a mother red kangaroo produces and raises an average of three young every two years. The female is in fact able to store a dormant embryo that will resume development and be delivered if a newborn dies or is prematurely removed from the pouch. Evidently the cessation of teat stimulation triggers this response. In some kangaroo species, the dormant embryo is simply a spare; it degenerates if not used to replace an ill-fated pouch-dwelling joey. In others, the dormant embryo automatically awakens after the normal maturation of the preceding one.

Uncertain Origin?

To most scientists, what the kangaroos’ ancestors were is still debatable. Evolutionists are generally agreed that all the Australian marsupials, including kangaroos, have ‘descended’, from small, perhaps pouchless, carnivores or insectivores capable of bearing large litters of young. Yet at least one expert admits that most species of fossil and living kangaroos are so specialized that they tell us little about their ancestry.

What are believed to be the oldest fossils of marsupials in Australia are supposed to be a mere 25 million years old, while the oldest indisputable kangaroo fossils are said to be 15 million years old. But those remains are very fragmentary and tiny isolated teeth and some foot bones that collectively ‘could fit comfortably into a cigar box’.

These and other ‘early’ teeth and bone fragments are easily identified as kangaroo remains, with no hint how the distinctive kangaroo hindlimb structure, for instance, could have evolved from some unknown hypothetical ancestor that couldn’t ‘hop’. To quote one expert:

Our understanding of the evolution of locomotion within the kangaroos is remarkably incomplete when compared with what is known of other systems, especially dental function and morphology [i.e. shape]. No post-cranial remains [i.e. bones other than head remains] are known for the species of several extinct genera, and many modern species remain unstudied from the viewpoint of locomotion. In virtually all cases, the osteology [i.e. bone anatomy and structure] of the hindlimb is so poorly understood in modern forms that it is impossible to interpret the significance of unusual structures in extinct macropodoids [i.e. kangaroos].’ (Flannery, 1983, p. 508)

With so much uncertainty, and fragmentary evidence that doesn’t support their case, all the evolutionists can do is imagine that some ‘Proto-kangaroo-cum-possum’ descended from some rainforest canopy to forage and then for some unknown reason decided to hop, the creature’s bones finally changing (gradually?) somehow to support this new form of locomotion.

When Man meets Roo!

Man is one of the kangaroos’ worst enemies. The Australian Aborigines hunted kangaroos as a major source of food and skins in the centuries before white Europeans came to Australia, without apparently making any dent in the total population numbers. Arrival of the first Europeans stepped up the slaughter, but without appreciable effect on the census until the pastoralists - with their sheep and cattle - began altering the environment.

Creating grasslands and waterholes for their livestock, the pastoralists inadvertently created a kangaroo paradise. At the same time they often destroyed the habitat of smaller species, thus reducing and sometimes eliminating entire populations. Red and grey kangaroos soon reached pest proportions, outnibbling sheep on improved grasslands and outliving domestic stock during long dry spells.

These bigger kangaroos also invaded both acreage in use and that withdrawn from sheep to recover its growth.

Fences went up, but they simply vaulted over them. The kangaroos sired progeny faster than farmers could gun them down. So began the slaughter of kangaroos which continues to this day. It is ironic that the kangaroo is the Australian national symbol on the one hand, but is shot as a pest on the other. Today, however, limits are placed on the numbers that can be slaughtered.

Kangaroo meat, containing more protein pound for pound than the meat of Australia’s sheep or cattle, is usually used for pet food, while their skins are prized for various fur-covered products. In recent years this has brought an outcry from some countries where our kangaroo products have been exported, such as the United States.

Today the legal culling of kangaroos is strictly controlled, to ensure that only those species which are a real problem are culled, thus leaving the smaller and usually rarer species opportunity to re-establish their numbers - so depleted in the past by the advent of European settlement in Australia.

Created

But there need be no uncertainty or imagination about the origin of Australia’s unique and amazing kangaroos. The Book of Genesis is quite emphatic that in the first week of history God created every kind of creature that has ever inhabited the earth. While kangaroos are not mentioned by name, we are told that God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind (Genesis 1:25), and this description certainly encompasses the kangaroo ‘kind’.

What’s more, the evidence emphatically agrees with Genesis. While genetic variation among the descendants of the original pair in the kangaroo ‘kind’ has resulted in today’s kangaroo family (see footnote), with all its different sizes and varieties inhabiting so many different environments, there are still distinctive features within genetic limits that make the kangaroo family distinctive from other marsupials.

Furthermore, the kangaroo displays all the evidence of planned, purposeful design at the hand of a Master Designer. Chance random evolutionary processes, whether gradual or in ‘jumps’, cannot even begin to explain the development of the hindlimb structure and long tail that give the kangaroo its unique locomotion ability. What is required is a precise combination of tail and hindlimb lengths, of bone shapes and configurations, and of muscles, not to mention the nerve fibres hooked up the right way with the brain to co-ordinate the whole process of ‘hopping’.

Always a Roo!

And the fossil evidence, though scant, confirms that kangaroos have always been kangaroos. This unique combination of bones and muscles is there right from the start, fully developed and functional, perfectly designed by the Creator, just as Genesis says.

And how does the hairless newborn kangaroo know and manage to crawl to its mother’s pouch across her fur? Its well-developed sense of smell through large nostrils directs it, while it coordinates its well-developed and active forelimbs, with claws, and jaw muscles to move sinuously but unerringly in the right direction.

Could all this develop by chance random evolution? Surely the newborn should have arrived with well-developed hindlimbs, since this is the adult kangaroo’s hallmark! But no, the hindlimbs are mere buds. Only an all-knowing Creator would design and execute such a marvellous integrated and coordinated plan with forelimbs well-developed at first and large nostrils to smell the way to the milk in its mother’s pouch, where milk of different chemical composition is supplied from different teats to satisfy the different needs of the newborn compared to the older joey-at-foot!

But why go to all that bother? To make a unique Australian, of course! The complexity, variety and beauty of the creation all around us serves to glorify the Creator and show forth His beauty, wisdom and power. To study Australia’s amazing kangaroo can only leave the humble student without excuse.

Footnotes and References

Footnote

It is not possible to say with certainty whether all which we now call kangaroo species were descended from only one original created kind. For example, the rat kangaroo group may be descended from another pair, and the similarities due to common design.

References

1. Flannery, T.F., 1983. Hindlimb structure and evolution in the kangaroos (Marsupialia: Macropodoidea)’. In: The Fossil Vertebrate Record of Australasia, P.V. Rich and E.M. Thompson (eds), Monash University, pp. 508 -523.
2. Flannery, T.F., 1984. ‘Kangaroos: 15 million years of Australian bounders’. In: Vertebrate Zoogeography and Evolution in Australasia, M. Archer and G. Clayton (eds), Hesperian Press, pp. 817-835.
3. Frith, H.J. and Coleby, J.H., 1969. Kangaroos, F.W. Cheshire Publishing Pty Ltd, Australia, pp. 110-119.
4. Sharman, G.D., 1979. ‘They’re a marvellous mob those kangaroos!’ National Geographic, 155 (2): 192-209.